The cytoskeleton in pathologic conditions

Intermediate filaments in Sertoli cells

Using immunohistochemical techniques both at light and electron microscopic levels, the arrangement and distribution of intermediate filaments in Sertoli cells of normal testis (in rat and human), during pre- and postnatal development (in rabbit, rat, and mouse) and under experimental and pathological conditions (human, rat), have been studied and related to the pertinent literature. Intermediate filaments are centered around the nucleus, where they apparently terminate in the nuclear envelope providing a perinuclear stable core area. From this area they radiate to the plasma membranes; apically often a close association with microtubules is seen. Basally, direct contacts of the filaments with focal adhesions occur, while the relationship to the different junctions of Sertoli cells is only incompletely elucidated. In the rat (not in human) a group of filaments is closely associated with the ectoplasmic specializations surrounding the head of elongating spermatids. Both in rat and human, changes in cell shape during the spermatogenic cycle are associated with a redistribution of intermediate filaments. As inferred from in vitro studies reported in the literature, these changes are at least partly hormone-dependent (vimentin phosphorylation subsequent to FSH stimulation) and influenced by local factors (basal lamina, germ cells). Intermediate filaments, therefore, are suggested to be involved in the hormone-dependent mechanical integration of exogenous and endogenous cell shaping forces. They permit a cycle-dependent compartmentation of the Sertoli cell into a perinuclear stable zone and a peripheral trafficking zone with fluctuating shape. The latter is important with respect to the germ cell-supporting surface of the cell which seems to limit the spermatogenetic potential of the male gonad.

Effects of partial hepatectomy on microtubules and hepatocellular transport of indocyanine green in rats

The effects of partial hepatectomy on plasma disappearance and biliary excretion of indocyanine green (ICG) have been studied in rats and correlated with morphometric changes of hepatocellular microtubules. The plasma disappearance rate of ICG was in good accord with recovery of liver weight after partial hepatectomy. Biliary excretion of ICG per 100 g liver significantly increased between 3 h and 7 days postoperatively. Colchicine significantly reduced plasma disappearance and biliary excretion of ICG, with no reduction in bile flow, in both intact and hepatectomized rats. Morphometrically, microtubules significantly increased from 3 h following partial hepatectomy and reached a maximum at 24 h with a gradual return to preoperative values at 5 days. These observations suggest that the increased hepatocellular transport of ICG after partial hepatectomy is related to an increase in the number of microtubules.

Actin-deficient cardiomyopathy coexisting with celiac disease: a chance association?

A case of idiopathic congestive cardiomyopathy associated to celiac disease is presented. The ultrastructural and electrophoretic examination of myocardial samples showed a selective loss of actin. Electron microscopy revealed the characteristic alterations of enterocyte microvilli seen in celiac disease. The involvement of the microfilament system both in the myocardial sarcomere and in the enterocyte may indicate a pathogenic relation between these alterations. Ultrastructural examination of skeletal muscle tissue showed a good preservation of the cell contractile apparatus.

Alveolar rhabdomyosarcoma in a young female patient metastasizing to the brain

A case of 14-year-old girl is reported in whom an alveolar rhabdomyosarcoma occurred in the soft tissues of the left forearm 4 years prior to death. Despite extensive surgery as well as chemotherapy and radiotherapy the tumor recurred locally and produced extensive metastases including a metastasis to the brain. Cerebral metastases have not yet been reported in the literature despite extensive reports on the pathology of alveolar rhabdomyosarcoma. The morphological diagnosis of rhabdomyosarcoma was supported by the immunohistochemical demonstration of desmin, myosin, and myoglobin in the tumor cells.

Immunohistochemical demonstration of cytokeratins in endocrine cells of the human pituitary gland and in pituitary adenomas

Ten non-neoplastic pituitary glands and 22 pituitary adenomas producing different hormones were studied by immunofluorescence microscopy as well as peroxidase-antiperoxidase and biotin-avidin techniques on frozen sections and formalin-fixed, paraffin-embedded material using antibodies to cytokeratin, vimentin, GFAP, neurofilament protein and different pituitary hormones. The endocrine cells in non-neoplastic pituitary glands as well as in most pituitary adenomas were cytokeratin-positive. The cytoplasmic cytokeratin distribution patterns of non-neoplastic and tumor cells were similar and typical of the type of hormone produced: GH-producing normal cells showed a paranuclear condensation of cytokeratin-reactive intermediate filaments; this accumulation was even further accentuated in GH-producing adenomas resulting in fibrous bodies (Kovacs and Horvath 1978) decorated by cytokeratin antibodies. Prolactin-producing cells showed a less intense cytoplasmic cytokeratin-specific staining with focal paranuclear accentuation in non-neoplastic as well as in neoplastic glands. ACTH-producing cells in normal pituitary glands as well as in adenomas exhibited a strong and more uniform cytoplasmic cytokeratin staining. The cytokeratin reactivity in glycoprotein hormone-producing cells of non-neoplastic tissue and adenomas was weak. Vimentin and GFAP reactivity was confined to agranular folliculo-stellate cells. The specific and different distribution patterns of cytokeratins in pituitary cells can, therefore, provide an (indirect) indication to the production of a specific hormone if immunocytochemistry fails to demonstrate hormone production.